WWB is all about ABSOLUTE positioning. Responsive site require relative positioning and lots of float:left or float:right in the CSS. So WWB is not suited to true responsive web design.

However, saying that Pablo has provided ways to acheive a responsive site - specifically the jQuery Masonry extension. I have produced a template based on the jQuery Masonry extension which you can find from the links in my signature. And the template you want to look at is number 4.